1. Field
The present embodiments generally relate to systems and methods for producing synthetic natural gas. The present embodiments relate to systems and methods for producing synthetic natural gas using low grade coal feedstocks or other carbonaceous feedstock.
2. Description of the Related Art
Clean coal technology using gasification is a promising alternative to meet the global energy demand. Most existing coal gasification processes perform best on high rank (bituminous) coals and petroleum refinery waste products but are inefficient, less reliable and expensive to operate when processing low grade coal. These low grade coal reserves including low rank and high ash coal remain underutilized as energy sources despite being available in abundance. Coal gasification coupled with methanation and carbon dioxide management offers an environmentally sound energy source. Synthetic or substitute natural gas (“SNG”) can provide a reliable supply of fuel. SNG, with the right equipment, can be produced proximate to a coal source. SNG can be transported from a production location into an already existing natural gas pipeline infrastructure, which makes the production of SNG economical in areas where it would otherwise be too expensive to mine and transport low grade coal. Alternatively, in developing countries, the production and supply of clean efficient SNG to densely populated cities instead of the transport and use of low grade coal as an energy source in a multitude of inefficient and polluting facilities within the cities provides the means to effectively mitigate pollutants and carbon capture.
A typical problem with SNG generation is the high auxiliary power and process water requirements. Often a large quantity of outside power is required to run a SNG production system, and a large quantity of water needs to be supplied to the SNG production system to accommodate the processes of the system. The large quantities of water and outside power needed to run the SNG production system can greatly escalate the cost of production and limit where SNG generation systems can be deployed.
A need exists, therefore, for more efficient systems and methods for producing SNG from coal that reduce the requirements for outside power and water.